gdb/linux-nat-trad.c

   1 /* Generic GNU/Linux target using traditional ptrace register access.
   2
   3    Copyright (C) 1988-2021 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "linux-nat-trad.h"
  22
  23 #include "nat/gdb_ptrace.h"
  24 #include "inf-ptrace.h"
  25 #include "gdbarch.h"
  26
  27 /* Fetch register REGNUM from the inferior.  */
  28
  29 void
  30 linux_nat_trad_target::fetch_register (struct regcache *regcache, int regnum)
  31 {
  32   struct gdbarch *gdbarch = regcache->arch ();
  33   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  34   CORE_ADDR addr;
  35   gdb_byte *buf;
  36   size_t size;
  37   pid_t pid;
  38   int i;
  39
  40   /* This isn't really an address, but ptrace thinks of it as one.  */
  41   addr = register_u_offset (gdbarch, regnum, 0);
  42   if (addr == (CORE_ADDR)-1
  43       || gdbarch_cannot_fetch_register (gdbarch, regnum))
  44     {
  45       regcache->raw_supply (regnum, NULL);
  46       return;
  47     }
  48
  49   pid = get_ptrace_pid (regcache->ptid ());
  50
  51   size = register_size (gdbarch, regnum);
  52   buf = (gdb_byte *) alloca (size);
  53
  54   /* Read the register contents from the inferior a chunk at a time.  */
  55   for (i = 0; i < size; i += sizeof (PTRACE_TYPE_RET))
  56     {
  57       size_t chunk = std::min (sizeof (PTRACE_TYPE_RET), size - i);
  58       PTRACE_TYPE_RET val;
  59
  60       errno = 0;
  61       val = ptrace (PT_READ_U, pid, (PTRACE_TYPE_ARG3) (uintptr_t) addr, 0);
  62       if (errno != 0)
  63         error (_("Couldn't read register %s (#%d): %s."),
  64                gdbarch_register_name (gdbarch, regnum),
  65                regnum, safe_strerror (errno));
  66       store_unsigned_integer (buf + i, chunk, byte_order, val);
  67
  68       addr += sizeof (PTRACE_TYPE_RET);
  69     }
  70   regcache->raw_supply (regnum, buf);
  71 }
  72
  73 /* Fetch register REGNUM from the inferior.  If REGNUM is -1, do this
  74    for all registers.  */
  75
  76 void
  77 linux_nat_trad_target::fetch_registers (struct regcache *regcache, int regnum)
  78 {
  79   if (regnum == -1)
  80     for (regnum = 0;
  81          regnum < gdbarch_num_regs (regcache->arch ());
  82          regnum++)
  83       fetch_register (regcache, regnum);
  84   else
  85     fetch_register (regcache, regnum);
  86 }
  87
  88 /* Store register REGNUM into the inferior.  */
  89
  90 void
  91 linux_nat_trad_target::store_register (const struct regcache *regcache,
  92                                        int regnum)
  93 {
  94   struct gdbarch *gdbarch = regcache->arch ();
  95   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  96   CORE_ADDR addr;
  97   size_t size;
  98   gdb_byte *buf;
  99   pid_t pid;
 100   int i;
 101
 102   /* This isn't really an address, but ptrace thinks of it as one.  */
 103   addr = register_u_offset (gdbarch, regnum, 1);
 104   if (addr == (CORE_ADDR)-1
 105       || gdbarch_cannot_store_register (gdbarch, regnum))
 106     return;
 107
 108   pid = get_ptrace_pid (regcache->ptid ());
 109
 110   size = register_size (gdbarch, regnum);
 111   buf = (gdb_byte *) alloca (size);
 112
 113   /* Write the register contents into the inferior a chunk at a time.  */
 114   regcache->raw_collect (regnum, buf);
 115   for (i = 0; i < size; i += sizeof (PTRACE_TYPE_RET))
 116     {
 117       size_t chunk = std::min (sizeof (PTRACE_TYPE_RET), size - i);
 118       PTRACE_TYPE_RET val;
 119
 120       val = extract_unsigned_integer (buf + i, chunk, byte_order);
 121       errno = 0;
 122       ptrace (PT_WRITE_U, pid, (PTRACE_TYPE_ARG3) (uintptr_t) addr, val);
 123       if (errno != 0)
 124         error (_("Couldn't write register %s (#%d): %s."),
 125                gdbarch_register_name (gdbarch, regnum),
 126                regnum, safe_strerror (errno));
 127
 128       addr += sizeof (PTRACE_TYPE_RET);
 129     }
 130 }
 131
 132 /* Store register REGNUM back into the inferior.  If REGNUM is -1, do
 133    this for all registers.  */
 134
 135 void
 136 linux_nat_trad_target::store_registers (struct regcache *regcache, int regnum)
 137 {
 138   if (regnum == -1)
 139     for (regnum = 0;
 140          regnum < gdbarch_num_regs (regcache->arch ());
 141          regnum++)
 142       store_register (regcache, regnum);
 143   else
 144     store_register (regcache, regnum);
 145 }